High speed portable facsimile system



1941. w. G. H. FINCH 2,253,332

HIGH SPEED PORTABLE FACSIMILE SYSTEM Filed Sept. 24, 1937 4 Sheets-Sheet1 Fig: :1

TRANSMlTTER J W; a a,

RECEIVER INVENTOR'. william gflm inch ATTORNEY.

Nov. 18, 1941. w F|NH 2,263,332

HIGH SPEED PORTABLE FACSIMILE SYSTEM Filed Sept. 24, 193? 4 Sheets-Sheet2 INVENTOR. william g..?fi inch ATTORNEY.

W. G. H. FINCH HIGH SPEED PORTABLE FACSIMILE SYSTEM Nov. 18, 1941.

4 Sheets-Sheet 3 Filed Sept. 24, 1937 127 rimn nmflglllml lllllhll ImmamI 1 M Inn MIIIIIIIH lllllll'llll Ill Ill

' nimunnm :1 5| l F'M Il F19 5 INVENTOR,

will-11am .Jt'. inch BY j 79:

TTORNEY.

Nov. 18, 1941. w. G. H. FINCH HIGH SPEED PORTABLE FACSIMILE SYSTEM IFiled Sept. 24, 1937 4 Sheets-Sheet 4 INVENTOR. william ghil' inchATTORNEY.

Patented Nov. 18, 1941 UNITED STATES PATENT OFFICE HIGH SPEED PORTABLEFACSIIMILE SYSTEM 2 Claims.

This invention relates to facsimile systems and more particularlyrelates to novel methods of and apparatus for transmitting and recordingpicture records at a high rate of operation.

Facsimil transmitters of the prior art operate with a rotatable drumupon which the picture to be transmitted is mounted, or employ a flatrecord sheet continuously feeding past the transmitter scanner. Thefacsimile recorders have hitherto corresponded to the transmitterscanners in that a rotatable drum recorder was used for a correspondingrotatable drum transmitter, and a continuous sheet or flatbed recorderwas used for a similar type transmitter.

In the transmission of facsimile records, it is most practical to usethe rotatable drum type of transmitter since the records to betransmitted usually come in relatively small lengths and are difficultto mount as a continuous sheet required for continuous sheettransmitters. the other hand, it is more practical, particularly forlayman operation of facsimile records, to receiv the successivefacsimile reproductions on a continuous sheet recorder. The obviousadvantage of a continuous sheet recorder resides in the minimum amountof readjustment and manual operations required to obtain the suc cessiverecordings. Where the facsimile recording is performed in the home oraboard an aircraft or moving vehicle, it is most desirable to have alarg roll of recording paper continuously fed past the receiving scannerto translate the signals as successive picture records on the sheetwhich is fed through the mechanism.

In accordance with my present invention I provide a novel facsimilesystem whereby a continuous sheet recorder is employed to translatesignals originating from a revolving drum transmitter. Thus, successivenews bulletins, news pictures, weather maps and the like may be mountedupon the drum of the transmitter and received in succession upon thecontinuous sheet recorder as though the successive transmitted recordswere being transmitted from a continuous sheet transmitter. Thepreferred transmitter I employ is of the removable drum type to enablethe operator to mount the successive pictures for transmission upon aspare drum during the interval of transmission of the pictures.

An important feature of my present invention is to provide a novel highspeed facsimile recorder employing a plurality of stylii successivelyoperating upon the record sheet to minimize the dead period heretoforenecessary in continuous sheet recorders. In a preferred form of myinvention I mount three stylii upon a continuously rotated belt orcarrier, spaced on the belt by a distance equal to the width of therecord sheet. The stylii are individually and successively moved intocontact with the record sheet to form line by line scanning transverselyacross the sheet to compose the reproduction. The stylii areelectrically interconnected to the rectified facsimile signals toelectrolytically or electrostatically break down the record sheet alongthe scanning region.

The record sheet at the receiver is continuously advanced past therecording region during the recording intervals. This continuousmovement of the record sheet is advantageous to form a slanted lin ofrecording along the sheet to correspond to the helical trace along thepicture being transmitted from the rotatable drum. This feature will behereinafter described in more detail and simplifies the feedingmechanism for the recording paper. The prior continuous sheet recordersemployed step by step line feeds which were advanced during thesynchronizing interval.

The facsimile recorder of my present invention is equally applicable towet or dry type electrolytic or electrostatic recording. A small tank isprovided for containing the liquid employed with the wet type process.ing operation the record sheet is by-passed across the tank and feddirectly to the scanner.

It is accordingly an object of my present invention to provide a novelmethod of and apparatus for transmitting and receiving pictures and thelike.

Another object of my present invention is to provide a novel facsimilesystem employing a drum type transmitter and a continuous sheet recordertherefor.

Still another object of my present invention is to provide a novelcontinuous sheet facsimile recorder unit.

A further object of my present invention is to provide a novelinexpensive multiple stylii facsimile recorder capable of very high rateof operation.

Still a further object of my present invention is to provide a novelcontinuous sheet recorder wherein the recording paper is continuouslyadvanced during the scanning periods.

Still a further object of my present invention is to provide a novelinexpensive rugged high speed continuous sheet facsimile recordersuitable for aircraft, home and mobile operation For dry typerecordhousing 22 at the rear of the carriage 20.

with a minimum of skill required for operation thereof.

Another object of my present invention is to provide a novel method ofand means for line by line synchronizing of multiple stylii facsimilerecorders.

These and further objects of my invention become apparent in thefollowing description of a preferred embodiment illustrated in thedrawings, in which:

' Figure 1 is a plan view of' a preferred drum type facsimiletransmitter.

Figure 2 is a diagrammatic representation of a preferred formfor themultiple stylii continuous sheet facsimile recorder of my presentinvention.

Figure 3 is a plan view of a preferred construction for the facsimilerecorder of my present invention.

Figure 4 is an end elevational view of the recorder of Figure 3, withthe drive motor removed.

Figure 5 is a side elevational view of the recorder of Figure 3.

Figure 6 is a vertical cross sectional view taken along 6-6 of Figure 3.

Figure 7 is a vertical cross sectional view taken through thesynchronizing drive mechanism along 'l-! of Figure 8.

Figure 8 is a horizontal cross sectional view taken along 8-8 of Figure4.

Figure 9 is an enlarged detailed view of the stylus.

Figure 10 is a cross sectional view taken along Ill-l of Figure 8.

Figure 11 is an end view corresponding to H-H of Figure 8 through theplaten drive mechanism.

Figure 12 is a cross sectional View taken along 12-12 of Figure 4through the synchronizing magnet.

Figure 13 is a horizontal view taken along l3-l3 of Figure 4illustrating the synchronizing details.

In carrying out my invention, I prefer to employ a rotatable drumfacsimile transmitter. Howevenit is to be understood that the continuoussheet recorder to be described is equally useful with a continuous sheettransmitter system.

The transmitter shown in Figure 1 corresponds to that described in myPatent No. 2,047,863, which issued onJuly 14, 1936, and is entitledTelecommunications systems. The picture In to be transmitted is mountedupon a rotatable drum II by means of a series of film clamps [2. Therotatable drum is removably mountable between the spindle l3 set in tailstock l4 and the drive plate l operated through reduction gearinglocated in housing l6 by means of synchronous motor l1 operated at apredetermined speed. The system is secured upon a heavy, cast iron base[8 to minimize vibrations.

The electrooptical scanning of the record or picture I0 is accomplishedby the apparatus housed in the transversely movable carriage 20.

The telescope 2| focuses a beam of light generated by a lamp sourcecontained in a ventilated When 100 lines per inch of scanning isrequired; the diameter of the scanning light beam 23 is made onehundreth of an inch. The beam 24 reflected from the record sheet I0 isfocused by lens system 25 upon a photo-electric cell contained in thecarriage 20 for producing an electrical ourrent varying in accordancewith the elemental shading of the picture being scanned as is well knownin the art. The electrical pulses are amplified by means of an amplifierpreferably contained in a movable housing 20 and conducted to thetransmitter 26 by a flexible cable 21.

The preferred rate of movement for the electrooptical scanner 28 is oneinch per minute in direction parallel to the axis of the picture drum II, Carriage 20 is motivated by a lead screw 28 coacting with a worm-locklocated beneath the carriage 20 and engageable and disengageable withthe screw 28 by means of the cam lever 29 mounted upon extension plate30 of the housing 20. The lead screw 28 is rotated at the necessaryspeed by means of a mechanical connection to the gearing system at I6through the intermediate gearing 3| and 32 and the drive shaft 33. Thescanner carriage 20 is accurately guided in its transverse movement bygrooved tracks 34-34.

As will now be evident, the scanning of the record sheet I0 is performedalong a continuous and contiguous helical path, as schematicallyindicated by the lines 35. The arrows adjacent the scanning region 35indicate the direction of movement of the sheet I0 and the scanner beamI prefer to employ a synchronizing signal generated once per revolutionof the drum II to maintain synchronous operation of the recorder scanneras will be described. The cyclic synchronizing impulse may be generatedby a cam 36 connected mechanically to the drum H and rotating therewith,together with a cam switch 31 coacting with the cam 36. Cam 36 containsa nib or projection 38 which actuates the cam switch 31 once perrevolution of the cam 36. Cam switch 31 is electrically connected byleads 39 to the transmitter 26 to generate the synchronizing signal in apreferred manner. My Patent No. 2,047,863 discloses one manner ofinitiating the synchronizing impulse or signal during the underlap ordead portion of the picture corresponding to the region of clamping byclamps l2.

The generated picture and synchronizing signals may be caused tomodulate a radio carrier wave or be directly transmitted by the wireline 40, or its equivalent, to the facsimile receiver indicated at 4|,Figure 2. The receiver is adjusted to amplify the facsimile signals andimpress them upon a push-pull transformer 42, the secondary of whichconnects to the control grids of a push-pull amplifier stage 43-43through a variable grid resister'44 for controlling the resultantamplitude of the facsimile signals at the recorder. I prefer to usescreen grid amplifiers for the push-pull stages 43. The cathode resister43 is connected between the cathodes of the stages 43 and ground forsuitably biasing the tubes in the conventional manner. Resister 45 isshunted by a bypass condenser 46. The output of the push-pull stage43-43 is connected through a push-pull coupling transformer 41 to a dualrectifier stage 48. The anodes 49 and 50 of stage 48 are connected tothe outer terminals of the secondary of the transformer 41. The cathode5| of the rectifier 48 serves as one terminal of the rectified signaloutput and corresponds to the positive terminal of the facsimilesignals. The mid-point 52 of the output transformer secondarycorresponds to the negative terminal of the facsimile signals. Theillustrated electrical recording circuit is disclosed in detail in mycopending application Serial No. 156,625,

filed July 31, 1937, and entitled Facsimile recorder. It is to beunderstood that different circuital arrangements for the transmitter andreceiver are feasible with the recording to be described.

A schematic representation of the multiple stylus continuous sheetrecording system forming an important feature of my present invention isshown in Figure 2. The sensitized record sheet 53 is motivated by meansof a metallic platen 54. A plurality of stylii 55 are mounted on acommon conveyor belt 56 and are moved along a predetermined region withrespect to the platen 54 to trace successive lines of scanning 51 uponthe record sheet 53, in a manner to be fully described hereinafter. Apreferred conveyor 56 comprises a steel belt having sprocket holes anddriven by the sprocket wheel 58. A coacting pulley 58 guides the belt 56in its predetermined path.

The electrical signals are impressed between the stylii 55 and thesensitive record sheet 53. I prefer to place the record sheet 53 at thehigh or positive potential side of the signals and illustrate themetallic platen 54 as connected to the cathode through connection lead68. The negative side of the signals is connected to the stylii 55through the metallic belt 56, the metallic idler pulley 59, connectionlead 61, synchronizing cam switch 62, and connection lead 63. The stylii55 and associated metallic conveyor 56 are electrically insulated fromthe remainder of the recording unit, as schematically indicated by theinsulation block connection 64 inserted in the drive rod 65 for thesprocket wheel 58. The metallic platen 54 is connected to the frameworkof the recorder which is preferably at ground potential.

The preferred electrical disposition of the facsimile signal outputconnections, making the sensitive record sheet 53 positive and thestylii negative, performs the useful function of preventing smudging ofthe recording due to small particles being removed during the electricalscanning action as fully described in my copending application SerialNo. 156,625, referred to hereinabove.

The motivation of the facsimile recorder is preferably through anelectrical motor 66 which is operated at a constant speed at or closelyadjacent the predetermined synchronous speed corresponding to the speedof the transmitter motor H. A preferred motor is a constant speed directcurrent motor having an electrical or mechanical governor control tomaintain con stant speed thereof. The shaft 61 of the motor 66 is gearedto a pinion 68 through intermediate gearing 68 and '18. The stylus driveshaft 65 is mechanically connectable with the shaft 1| by means of afriction clutch I2. Clutch 12 comprises two discs 13 and 14interconnected by a friction member such as felt pad 15. The clutchplate 13 is slidably secured to the shaft H and is mechanically biasedagainst the friction plate 15 by the spring 16, one end of which is fastened to the shaft H by nut 11 and the end of which is secured to thefriction plate 13. A continuous drive connection is accordinglyestablished between the motor 66 and the sprocket drive wheel 58 for thestylus conveyor belt 56.

The record sheet 53 is moved transversely to the stylii 55 continuouslyat a predetermined rate. A gear connection to the stylii drive shaft 65and geared at the proper ratio serves to drive the platen 54 during themovement of the stylii 55. Figure 2 has illustrated a bevelled gearconnection 18 between shafts 18 and 65. A pinion or worm is secured tothe shaft 19 and coacts with a larger gear 8| which is mounted on shaft82 connected to the platen 54. Gear ratios are designed to move sheet 53at the predetermined rate corresponding to the transverse movement ofthe electrooptical scanner 20 at the transmitter, for example one inchper minute in a practical embodiment. The corresponding movement of thestylus 55 across the record sheet 53 is preferably equal to the rate ofscanning of the record sheet l0 along scanner lines 35.

The width of the record sheet 53 is substantially equal to thecircumferential length of the transmitter record sheet l8 in order thatthe successive scanning lines 51 at the receiver will correspond inlength and position to the scanning lines 35 at the transmitter. Thedistance between the stylii 55 is exactly equal to the circumference ofthe transmitter drum ll. When three stylii are used on the commonconveyor belt 56, the total length of the belt is equal to three timesthat of the circumference of the transmitter drum II. The rate ofrotation of the sprocket drive shaft 65 is designed to produce a linearrate of stylus belt 56 equal to the circumferential speed of thetransmitter drum II, as will now be evident to those skilled in the art.

Since the record sheet 53 is being advanced simultaneously with thetransverse movement of the stylus 55, the successive scanning lines 51traced upon the sheet 53 will be slightly inclined, as indicated inFigure 2. This inclination corresponds to the similar helical angle orinclination of the scanning lines 35 at the transmitter. The receivedpicture will accordingly have the identical relative scanning as thetransmitter to produce an accurate facsimile thereof. A continuousfeeding of the record sheet 53, as in the manner described, avoids theprior art step by step feeding operation and provides a smoother feedingof the record sheet.

In order to permit the operator to withdraw the recording on the recordsheet 53, and not interfere with subsequent recordings, I provide a pawl83 and ratchet 84 arrangement. Ratchet 84 is secured to the platen shaft82; and pawl 83, to gear 8|. The pawl and ratchet 83-84 is a positivedriving connection between gear 8| and shaft 82. However, should thepaper 53 be withdrawn manually at a faster rate than the feed rate ofthe sheet 53, the pawl and ratchet will permit the slipping of theplaten 54 so that the record sheet 53 may be readily moved and thesuccessive scanning will continue as heretofore after withdrawing of anintermediate length of sheeting.

Synchronous operation of the stylii 55 is obtained by line by linesynchronizing mechanism responsive to the cyclic synchronizing impulsetransmitted. A synchronizing cam 85 is secured to the shaft 19 and isdesigned to rotate three times per revolution of the stylii belt 56,corresponding to the one revolution per scanning line of the recorder. Anib 86 projects from cam 85 and cooperates with the synchronizing camswitch 62. The lever arm 61 of switch 62 bears upon the contact 88 formaintaining the recording circuit between the stylus 55 and record sheet53 normally closed during the scanning cycle. However, during thesynchronizing period of the cycle, corresponding to the underlap periodof the transmitter drum II, and occurring between the ending of onescanning line and the beginning of the next successive scanning line,the cam nib 86 moves against the lever arm 81 of switch 62 to open itscontact with arm 88 conmeeting it to the third arm 89 of the switch. At

this interval, which may be as much as 15% of the scanning line period,the rectified output of the detector tube 48 is connected to thesynchronizing relay 90. During this interval, the synchronizinginterval, the rectified synchronizing impulse being transmitted,energizes the relay 90 to close the armature 9| against the contact 92to locally energize the synchronizing magnet 93 through the battery 94.

The driven friction plate I4 contains a projection or nib (not shownsince it is positioned in the rear of th plate I4 as viewed in thediagram) which abuts one end of the armature 95 resting against theperiphery of the plate I4. I prefer to rotate the shaft 65 and 'II at arate of about one per cent faster than the normal arrival of theprojection on the plate I4 against the armature 95 at an instant beforethe reception of the synchronizing impulse. When the synchronizingimpulse is received and synchroattracted to the magnet 93 away from thestop plate I4, permitting the continuedrotation of the driven frictionplate I4 through the friction clutch I2. The movement of the stylus 55is accordingly started at the proper instant in the beginning of eachscanning line operation in exactphase with the corresponding startingposition at the transmitter drum, as will now be evident to thoseskilled in the art.

It is to be understood that line by line synchronism. is maintained withthe continuous sheet recorder having the multiple stylii as represented.Prior synchronizing systems having multiple stylii effected synchronismonce per revolution of the stylii and the facsimile results were notsatisfactory, since the successive dis placements of the scanning lineswere more material and more erratic than is possible with the line byline synchronism attained by my present;

invention. It is to be further understood that my present invention maybe practiced with more or less than the preferred three styliiarrangement illustrated.

A high rate of mechanical scanning is afforded:

by the mechanism of my invention. It is feasible to operate the systemwith 200 and more scanning lines per minute without affecting themechanical accuracy of scanning and the like.

The only limitations to the high rate of scanning reside in the width ofthe electric band to be transmitted, which corresponds to the number ofelemental picture impulses transmitted per second, and thereforecorresponds to the total linear length of scanning effected during eachFigures 3 to 13 represent details of a preferred physical embodimentof afacsimile recorder carrying out the principles of my inventionhereinabove described. Figure 3 is a plan view of the recorder with thecover removed illustrating the synchronous rate for the system to insurethe nizing magnet 93 energized, the armature 95 is roll of recordingpaper I00 rotatably supported in brackets IOI--IOI. The recording paperI00 is passed over guide rollers I02 and around platen I03. Presserrollers I04 are arranged to press against the sheet I00 near the regionof scanning. Rollers I04 extend from brackets I05, mounted upon a rodI06 supported between frame standards I01 and I08. Electrical motor I09is supported upon the cast iron base H0 of the recorder unit and isarranged to drive the stylii and recording sheet in a definite manner.Motor I09 is preferably a constant speed direct current motor having anelectrical and mechanica1 speed governor control housed within to drivethe apparatus at synchronous speed. The synchronous speed of the motoris determined by means of the checkered disc III in conjunction with aslot tuning fork by stroboscobic action in a manner well known in thesynchronizing art.

Figure 4 is an end elevational view of the recorder shown in Figure 3with the motor I09 removed to show the front elevation of the stylusconveyor II2. I prefer to use a steel belt for II 2 containing sprocketholes II3 along its mid-section as illustrated. In the preferredinstrument, three stylii II5 are shown equi-distantlymounted upon theconveyor belt I I2. The separation between the stylii H5 is equa1 to thelength of one scanning line and corresponds to the circumferentiallength of the transmitter drum or length of the scanning operation atthetransmitter. The stylus conveyor H2 is arranged to be driven by suitablegearing connection from the motor I09 through the intermediate frictionclutch member H6 and the drive sprocket wheel II'I. An idler or guidepulley I I8 is arranged opposite the sprocket drive wheel I I! tomaintainthe belt II2 taut and in positive alignment and coaction withthe record sheet Figure 5 is a side elevational view of the recordershown in Figures 3 and 4 showing further details of the mechanical drivearrangements and disposition of the recording paper I00. The roll ofrecording paper I00 is rotatably mounted on brackets IOI.' The paper I00is passed about the idler or guide rollers I02. One of the rollers I02is immersedin the tank I20 which contains a suitable liquid necessaryfor the electrolytic action of the stylus on the sheet I00 as will behereinafter described in more detail.

Motor I09 is geared to the pinion I2I through the intermediate gear I22and I23 as shown in Figure 5. Pinion I2I operates the sprocket wheel IIIthrough the intermediately arranged friction clutch H5 in a manner to bedescribed in detail in connection with Figure 7.

As seen in Figures 3, 4 and 7, a pinion I24 is mounted upon the top ofthe vertical driven shaft I 4| for further driving the record sheet I00as will be shown. The sprocket drive Wheel II! is secured to thevertical shaft MI and rotates therewith. In Figure 5, the pinion I24 ishidden behind the gear I25 meshing therewith as seen in Figures 3 and 4.Gear I25 is mounted upon an independent shaft I25a set in the frame.Pinion I25 is secured to the same shaft I25a with gear I25 and mesheswith a further gear I26. Gear I26 is directly connected to the worm I28through the shaft I21 which drives the worm gear I29 which, in turn,rotates the platen I93 for driving the record sheet through the unit ina positive manner. A plurality of gears I24, I25,

I25 and I26, in conjunction with the worm and worm gear arrangementI28-I29, serves to reduce the speed of rotation of the platen I03 withrespect to the rotation of the sprocket drive III, so that the platenwill advance the record sheet by a distance equal to the width of onescanning line during the execution of the excursion of one stylus H5across the record sheet I00. In the illustrated embodiment, one rotationof the vertical shaft I4I rotates the sprocket Wheel III once and movesone of the stylii II5 across the sheet I to execute one scanning line.The movement of the record sheet I00 is .01 inch during the execution ofone scanning line to give a scanning dilferential of 100 lines per inch.

Figure 6 is a vertical cross-sectional view taken along 6--6 of Figure 3transversely through the recording unit. The progress of the recordsheet I00 from the roll I09 is clearly shown in this view. Sheet I00 isimmersed through the liquid in tank I20 when a damp or wet recordingprocess is employed. A wiper plate I35 supported in a strip I36 pressesthe wet sheet I00, as illustrated, to squeeze out the excess liquidtherefrom. When a dry process is employed, it is unnecessary to pass thesheet through tank I20 and the sheet is directly passed about guideroller I02a along the dotted position I00a. A guide plate I31 supportsthe record I00 after it emerges from the platen I03.

For a suitable dry process recording, I employ a carbon content paperhaving a mercury oxide coating which produces a black picture upon anorange background, or a. silver nitrate solution on a white paper toproduce a black on white result. For the wet process, I employ ordinarywhite paper which is passed through a solution of iodide of starchcontained in the tank I20 resulting in a sepia or brown. finishedresult. A further dry process employs paper containing barium iodidepassed through water contained in tank I20 to dampen the paper forelectrolytic recording thereon resulting in a black-white picture.

Figure '7 is a vertical cross-sectional view taken along I-I of Figure 8through the synchronous driving mechanism. The lower gear or pinion I2Iis secured to the bushing I40 concentric about and rotatable withrespect to the central shaft I4I of the drive. The gear I2I is directlyand continuously driven by the electric motor I29 through intermediategearing I22 and I23 clearly illustrated in Figures 3 and 5. Set screwI42 secures the hub of gear I2I to the lower end of the bushing I40. Theupper end of the bushing I40 is arranged to drive the lower plate I43 ofthe friction clutch H6. The hub of drive plate I43 is slidably securedto the bushing I40 by a feather key I44. Spring I45 is set between a nutI46 and the bottom of the hub of friction plate I43 to mechanically biasthe friction plate I43 against the friction pad I41 of the clutch II6.Friction pad I4! is preferably felt, although ma terials such as rubberor fiber may be employed.

The upper drive plate I48 of clutch H6 is pinned to the central drivenshaft I M by pin I49. The shaft MI is vertically supported in bushingsmounted in the bracket I08. The hub I50 of the driven friction plate I48is fastened to the sprocket driver II-l by set screw II. The styliiconveyor belt I I2 is carried by the wheel II! in a manner to be furtherdescribed in detail in connection with Figure 8. Driven friction plateI48 contains a projection or nib I52 for coaction with the synchronizingmagnet to maintain the driven belt H2 in phase synchronous position aswill be further described hereinafter.

In carrying out my invention, the stylii II5 are maintained at anindependent voltage with respect to the record sheet I00 forelectrostatic or electrolytic recording. Accordingly, the stylii I I5and associated conveyor belt I I2 are insulatingly mounted with respectto the framework of the system. As shown in Figure 7, a preferredmounting for the belt H2 is to construct the sprocket wheel Ill and thetwo sections I53, the inner section; and I54, the outer section. Thinner section and outer section I53 and I54 comprising sprocket wheelII! are screwed together by screw members I55. The inner sprocket memberI53 is made of insulation material. The outer sprocket member I54 ispreferably made of aluminum or an alloy to have adequate wearingcharacteristics in use.

Figure 8 is a horizontal cross-sectional view taken along 6-8 of Figure4 through conveyor H2 and associated driving mechanism. Belt IIZ, aflexible steel belt having perforations H3 at regular intervals forpositive drive coaction with the sprocket wheel III, is arranged aboutthe drive sprocket wheel II! and the driven sprocket wheel H8. Thestylii II5 are symmetrically arranged equidistant about the belt II2. Iprefer to employ three stylii II5, as shown, although fewer or more mayequally well be employed with my invention. In this construction and inthe illustrated embodiment, I construct the diameter of the sprocketwheels I I1 and H8 so that their circumference is equal to one third thelength of the belt II2. I arrange the sprocket pins I56 in driversprocket III to engage with the sprocket holes H3 in a positive manner.

Figure 9 is an enlarged detailed view of the stylus II5 mounted upon theconveyor belt II2. Stylus II5 consists of a pin I60 set into a bushing I6| which is welded or soldered to the belt II 2 at the positioncorresponding to one of the sprocket holes H3. Th stylii II5 arearranged to project into a particular opening I62 in the drive sprocketIII, the sprocket hole I62 corresponding to a position of the sprocketpins I56.

The idler pulley II8 carries the belt II2. Fig. ure 10 is across-sectional view taken along I0-I0 of Figure 8 through the idlerpulley II8. Pulley II8 contains a recess or cavity I64 of the pulley foradmitting the bushing of the stylii I I5 projecting beyond the belt II2.Pulley III! is insulatingly mounted with respect to the frame andbracket mounting I0'I of the machine. One method is to have a metallicor aluminum bushing rotatably mounted upon a rod I65 set in the bracketI01 in insulation bushings I66 and I61.

Pulley II8 contains projecting flanges I68 for accurately centering thebelt II2. Electric contact is made to the stylii II5 through the beltII2 by its frictional contact with the metal pulley I I8 and therotational friction contact; of the hub of pulley II8 with thesupporting shaft I65. An electrical lead I65a is connected to the driveI65 for electrical connection with the facsimile signals. Lead I65acorresponds to the connection lead 6| of Figure 2 and is the negativepotential lead for the signals. As described in connection with Figure2, the positive potential lead for the signals is connected to theframework of the facsimile recorder, which preferably is a groundedpotential and is conductively connected to the metallic platen I03coactlng with the record sheet ing lever I8I with the friction plateI48. solid position of the lever I8I pivoted at I82 con- I duringrecording. Referring to Figure 8, the stylii II are shown to coact withthe record sheetI00 carried by the platen I03. Platen I03 is preferablyconstructed of brass for conductively connecting the paper I00 to theframework through brackets I01 and I08. Platen I03 is secured to acentral shaft I33 set in brackets I01 and I08. Shaft I33 of platen I03is driven by a worm and worm gear arrangement I28--I20, as shown inFigures 5, 8 and 11.

Worm I28 is connected with a positive driving connection-"to thestylii-belt drive as hereinabove described in connection with Figures 2and 5.- Figure-11 is a side view corresponding to II- I I- in Figure-8to illustrate the preferred drive-connection for the platen I03. A pawlI10 is-secured to worm gear I29. A ratchet I1l is pinned'to the shaft-I33of platen I03. Pawl and ratchet arrangement I10-I-1 I drives theplaten in-a positive manner through the worm and worm gear arrangementI28I28, and yet permits theindependent rotation of platen which occurswhen therecord'sh'eet I00 is manually withdrawn from the recorder. Thesynchronizing details for maintaining the system in line by linesynchronism is thoroughly described in connection with the schematicFigure 2 hereinabove. The synchronizing cam I15, corresponding to thecam 85 in Figure 2, is mounted upon shaft I4I, as shown in Figures 4, 5and "1. Cam I actuates cam switch I16 mounted upon bracket I08. Thesynchronizing magnet I11 is supported from rod I06, as shown in Figures3 and 4. Figure 12 is an enlarged detailed view through I2-I2 of Figure.4 of the synchronizing magnet I11'and its mounting on shaft I06 by meansof a block I18 secured to shaft I08 and a bracket I19 extending fromblock I18. Synchronizing magnet I11 is-arranged to attract armature I80secured 'to lever I8I in response to a receivedsynchronizing signalimpulse, as will be understood by those skilled in the art. The leverI8I is pivoted at 182 on bracket I08 as seen in Figure 4. Lever I8I isarranged to ride on the periphery of upper friction plate I48 I of thefriction clutch -I I6 as viewed in Figure 2. Figure 13 is a view takenalong I3I 3 of Figure 4 to demonstrate the coaction of the synchroniz-The tacts the periphery of plate I48; A projection I52 of plate I48abuts thetip'l83 of lever I8I while it is in the solid position.Thisoccurs when the driven frictionplate I48 reaches the predeterminedposition shown before the synchronizing signal is impressed upon magnetI11. At the instant the signal reaches magnet I11, armature I80 isattracted thereto and lever I8I is moved to the dotted position shownin-Figure 13, lifting the tip I83beyond the position of the projectionI52 to permit the driven friction clutch member I48 to execute onerevolution. The synchronizing signal occurs for a small portion of therotation cycle and lever I8I'falls to the position shown insolid toagain effect synchronizing control on the-driven member I48.

Accurate phase synchronism at the-start of each line is accordinglyafforded by the multiple stylii recorder and novel synchronizingarrangement. The friction clutch -member I48 is secured to shaft I4I, asillustrated at Figure .7 which drives the sprocket driver H1 and theplaten I03 as hereinabove described. The gear ratios ;from shaft I4Icontrolled by friction plate member I48 are arranged so that onerevolution of'the shaft I4I corresponds to the movement of one of thestylii II5 across the record sheet. The circumference of the sprocketwheels H1 and H8 is equal to the distance between the stylii II5 whichdistance corresponds to-the circumferenceof the drum at the transmitter.The synchronizing signal occurs at the end of each scanning line toaccurately position the stylii I I5 at the beginning of each scanningline maintain accurate phasing and synchronous recording by thesuccessive stylii on the record sheet I00.

In the illustrated embodiment, for example as shown in Figure 2, apositive drive connection is shown between the mechanism for motivatingthe stylii 55 across the record sheet 53 and the mechanism for feedingthe record sheet53 including the platen 54 and the associated gearing to84. This positive driving connection is designed so that the ratio ofgearing is such as to maintain a predetermined movement for the stylii55 and the record sheet 53, in the preferred embodiment corresponding tothe related movements at the transmitter in the rotation of the drum IIand the movement of the scanner carriage 20 transverse to the drum. Inorder to scan the record sheet along the lines 51 with an angleequivalent to the helical angle of the scanning lines 25 at thetransmitter, the ratio of the transverse movement of thestylii 55 andthe continuous advancecof the record sheet 53 axially should equal theratio of the peripheral velocity ofthedrum II while rotating, and thetransverse motion of the scanner carriage 20, as will'now beevident tothose skilled in the art. It is not necessary that the length of therecord sheet: 51,be identical with that of the periphery. or thecircumference of the drum; a proper contraction or enlargement in the.reproduction being entirely permissible, as will be realized by thoseversed in the facsimile art. The synchronizing mechanism including themagnetj93 and the clutch 12 operate, in response to a transmitted cyclicsynchronizing signal, to maintain the recording apparatus in phasesynchronismwith the transmitter drum II. The stylii 55 are arranged in apredetermined manner in relation with the positive feeding of the sheet53 to start at one end of the sheet at the beginning of each scanningcycle, corresponding to the. underlap portion of the record I0 asclamped on the transmitter drum II,

Although the illustrated embodiment shows a plurality of stylii 55 movedin a linear path along a recording'sheet 53 maintained in a linearscan-. ning region, it will now be obvious that a different arrangementfor the stylii or corresponding recordingunits is feasible and may beused with the principles of my invention. Thus the arrangement'of aplurality of recording units symmetrically about 'arotatable axis may bemade to cooperatewith a recording sheet 53 held in an arcuate scanningpath' to successively cooperate with the rotated multiple stylii. vThestylii in this modification would trace the scanning lines 51successively during each rotation of the com mon .carrierfor the stylii.The synchronizing arrangement for the multiple stylii rotated aboutacommon axis will be similar to that illustrated in connection with thestylii carried by a continuous belt 55 in that the cyclic synchronizingimpulse transmittedonce per revolution of the drum I I would beemployedto actuate the motiva tin'g mechanism for the stylii after eachtrace of one recording unit across the recording sheet.

It will thus be evident that the important contribution of my presentinvention resides in the recognition and solution of the problem formaintaining a multiple recorder system in synchrom'sm for reproducing afacsimile, namely the step by step synchronism for each of the pluralityof recorder units or stylii between the execution of the recording foreach unit or stylus upon the record sheet.

Furthermore, it will be evident that my present invention is not limitedto a recording system where the record sheet is continuously advancedduring the recording period. The step by step synchronizing of therecorder units or stylii may be accomplished without maintaining thepositive drive connection 80 to 84 between the stylus motivatingmechanism and the sheet feeding mechanism as shown in Figure 2. It isobvious that a step by step advancing means may be employed for therecord sheet 53 which sheet could be advanced between the successivescanning line recordings, namely during the synchronizing interval forthe multiple recording units. The individual recording units may haveelectromechanically actuated stylii for impinging upon the record sheetsuch as shown and described in my Reissue Patent No. 19,575. Such unitswhen arranged in a multiple unit, for example three, to embody the highspeed recording principles of my present invention, would essentiallyconsist in the placing of three stylii one hundred twenty mechanicaldegrees apart and in a single plane adapted to be rotated in a singledirection by the driving motor. It is to be understood that thesynchronizing arrangement would accordingly be effective for each thirdof a revolution of the stylii carrier shaft, corresponding to thesimilar phase synchronizing action for each third of a revolution of thecontinuous belt carrier 56 for the stylii 55 in Figure 2. At any rate,the principles of my present invention may be embodied in variousmodifications for facsimile transmission and reception without departingfrom the broader spirit and scope of the invention, and accordingly I donot intend to be limited except as set forth in the following claims.

I claim:

1. A facsimile system including a transmitter having means forgenerating signals in accordance with the elemental shading of a recordcomprising a rotatable drum for carrying and rotating said recordtherewith and mechanism for scanning the record on said drumtransversely of the rotation of the drum whereby said record is scannedin a continuous helical path, means for generating a synchronizingsignal cyclically in accordance with the rotation of said drum once perrotation of said drum and means for transmitting said generated signals;and a receiver having means for translating said signals including acontinuous sheet recorder comprising means for continuously feeding arecording sheet at a predetermined rate past a predetermined scanningregion during the recording periods, a plurality of stylii forsuccessively individually recording a line of scanning on said sheet atsaid scanning region and means for successively motivating said styliialong said record sheet at a rate substantially equal to the peripheralvelocity of said drum, a positive driving connection between saidfeeding means and said motivating means for maintaining the ratiobetween the axial and transverse scanning movements for said sheetcorresponding to the related movements for the record on said drum andmeans responsive to said synchronizing signals for controlling saidfeeding means in phase synchronism with said scanning mechanism and foroperating said motivating means into phase synchronism with the rotationof said drum.

2. A facsimile system including a transmitter having means forgenerating signals in accordance with the elemental shading of a recordcomprising a rotatable drum for carrying and rotating said recordtherewith and mechanism for scanning the record on said drumtransversely of the rotation of the drum whereby said record is scannedin a continuous helical path, means for generating synchronizing signalsonce per rotation of said drum and means for transmitting said generatedsignals; and a receiver having means for translating said signalsincluding a continuous sheet recorder comprising means for feeding arecording sheet past a predetermined scanning region during therecording periods, a plurality of recording units for successivelyindividually recording a line of scanning on said sheet at said scanningregion and means for successively motivating said recording units alongsaid record sheet at a predetermined scanning rate and means responsiveto said synchronizing signals for operating said motivating means intophase synchronism with the rotation of said drum after the operation ofeach of said plurality of recording units on said sheet.

WILLIAM G. H. FINCH.

